The desire to have the hair retain a particular shape or style is widely held. The most common approach for accomplishing styling of hair is the application of a composition to dampened hair, after shampooing and/or conditioning, or to dry, styled hair. These compositions provide temporary styling benefits and can readily be removed by water or shampooing. To date, the materials employed in hair care compositions to provide styling benefits have generally been natural or synthetic resins and have been applied in the form of, for example, sprays, mousses, gels and lotions.
Recently, it has become desirable to have a high level of style retention, or strong hold, delivered from a hair spray composition. In a typical hair spray, hold is achieved by the use of commercially available styling polymers, such as AMPHOMER (™), supplied by National Starch Chemical Company, LUVIMER(™), supplied by BASF, GANTREZ(™), supplied by ISP Chemicals and also silicone graft copolymers, supplied by Mitsubishi Chemicals.
Typically, the styling polymers have a carbon backbone comprising various hydrophilic and hydrophobic vinylic monomers. These polymers can be nonionic or they can carry a charge, usually a negative charge. The hydrophilic monomer is employed to render the polymer water-soluble and the hydrophobic monomer is generally selected to enhance humidity resistance of the styling resins. Traditionally, the anionically charged resins are formed from the corresponding acids (neutralised) using alkalising agents such as sodium or potassium hydroxide as well as certain functional amines such as aminomethyl propanol (AMP) to tailor their solubility and film forming properties.
The hydrophobic/hydrophilic character of modern styling resins is carefully balanced to produce materials that are soluble in hydroalcoholic solvents, typically 80% volatile organics content (VOC). To improve the performance of modern styling products even further, non-volatile plasticisers such as propylene glycol, dipropylene glycol, acetyl tri-n-butyl citrate and acetyl tri-2-ethoxyhexyl citrate (Citroflex(™)) have been employed in the compositions.
The conventional hair styling compositions require a relatively high VOC in order to solubilise the hair styling polymer. It is desirable, for economic and environmental reasons, to reduce the VOC of hair styling compositions.
Cyclodextrins (CDs), are cyclic oligosaccharides which may be derived from starch, or which can be obtained in other ways. Cyclodextrins were discovered about 100 years ago and have been used in the pharmaceutical and food industries for encapsulation of drugs and flavours. Cyclodextrins have also been used as processing aids, to isolate compounds from natural sources and to remove unwanted compounds such as cholesterol from food products.
The natural CDs are produced from starch by the action of cyclodextrin glycosyl transferase (CGTase), an enzyme produced by several organisms. Structurally, CDs consist of 6, 7, 8 and 9 (α, β, γ and δ, respectively) glucose units. They are typically shaped like conical tubes or buckets with a hydrophobic interior and a hydrophilic exterior. CDs are able to enclose a wide range of functional molecules as guests into their cavities, as described by, for example M L Bender; M Komiyama, Cyclodextrin Chemistry, Spring-Verlag, Berlin, 1978.
While there are many examples of inclusion complexes of small molecules with cyclodextrins in the literature, there are only few reports on the formation of such complexes with polymeric materials. For example, some attention has been given to produce polyrotaxanes containing cyclodextrins and side chain polyrotaxanes have been prepared and characterised (G. Wenz, Angew. Chem, Int. Ed. Eng. 1994, 33, 803 and M. Born and H. Ritter, Angew. Chem, Int. Ed. Eng. 1995, 34, 309).
Most recently, cyclodextrins have been utilised-in the free radical polymerisation field (J. Jeromin and H. Ritter, Macromol. Chem. Rapid Commun. 1998, 19, 377).
The use of cyclodextrins to remove odour in hair cosmetics is described in EP-A-0469232. Similarly, EP-A-0246090 teaches the use of cyclodextrins for the inhibition of perm odour.
A hair conditioning composition which comprises a visible breakable particle optionally comprising a cyclodextrin is disclosed in WO 00/40211. The compositions are not styling products and it is clear that any cyclodextrin could not assist in solubilising a polymer.
JP-A-7309722 describes hair cosmetic compositions comprising hydroxylated cyclodextrin and a high molecular weight silicone.
There is no suggestion in the prior art that a cyclodextrin could be used to increase the solubility of a polymer in a hair styling composition.
It is an aim of the present invention to provide cosmetic and personal care compositions in which the hair styling polymer has a greater aqueous solubility and which, therefore, may be formulated with a greater proportion of water as solvent.
It is a further aim of the present invention to provide other advantages in cosmetic and personal care compositions. For example, compositions of the invention may, surprisingly, have one or more advantageous properties selected from low tack polymer film characteristics, and when applied to hair can give improved hold of hair and/or enhanced shine of hair and/or better natural movement of hair.